Jassper,

Too bad you do not have a digital camera. I still wonder what makes the fluid go back in the reservoir when the unit cools down. I was assuming centrifugal force sent it out but I cannot figure out why it obediently returns when the unit cools off. Especially if the entry port is blocked off by the bimetallic spring having cooled down first. Any idea? Since you have had yours apart maybe it is obvious to you. From here it sounds kind of peculiar. Thanks, Jim

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Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)